1. Field Of The Invention
This invention is directed to viewers for sorting machines and to an illumination system for a viewer apparatus for a sorting machine that sorts objects, and, in one aspect, to such a viewer and system for uniformly illuminating an object to be sorted by employing one or more reflectors.
2. Description Of Related Art
The prior art discloses a variety of object sorting apparatuses. In general, these apparatuses have devices for viewing each object and for determining, based on color, whether or not a particular object is desirable or undesirable. Attempts have been made to uniformly illuminate the objects so that the viewer receives an accurate image. But there are a variety of problems associated with prior art illumination systems.
In some prior art apparatuses light is radiated from above onto an object to be viewed, thus producing a shadow on the bottom of the object, a dark area which a viewer may misinterpret as a defect. Shade rings employed to prevent light from going directly from a light source into a viewer do not alleviate the uneven bottom lighting. The use of light sources beneath the object produces a viewer of relatively large dimensions and thus requires that the object move a considerable length before an ejector can act on it. Due to variance in object size and weight, object speed, and ejector speed, it would be difficult to accurately eject only those objects to be ejected with a viewer of such large dimensions. Also, additional light sources require additional maintenance and repair, as well as additional diffusers or shade rings to prevent light from directly entering a viewer. Some prior art devices employ metal covers around lamp filaments to prevent light from directly lighting an object to be sorted, the light reflected onto the object rather than striking it directly.
Typical prior art sorting machines are shown in U.S. Pat. Nos. 3,028,960; 3,914,601; 4,057,146; 4,699,274; 4,513,868; 4,697,709 and 4,454,029 (both commonly owned with the present invention); and U.K. Patent Application 2,l36,957A.
There has long been a need for an effective and efficient illumination system for a viewer for a sorting machine. There has long been a need for such a viewer which provides uniform lighting of objects to be sorted, yet which is small enough so that effective object ejection is possible. There has long been a need for such illumination systems and viewers with which substantially all of an object's surface can be lighted.